base level

Base level refers to the lowest or foundational level of a system, structure, or measurement from which other levels or increments are built or understood. It provides a reference point or starting position. For example, in geography, the base level of a river is its original, natural level before any human intervention like damming or straightening. In general use, it can mean the fundamental standard or starting point for comparison. Recognizing the base level helps in understanding how higher levels relate or change relative to this foundational point.